Deciding what to do with your money is a complex decision, requiring lots of different parts of the brain to work together. But just before you make your conscious decision, a single neuron can reveal what you're going to choose.

The brain assembles a complex network of different areas that can evaluate the various benefits of spending your money now - taking the immediate reward - or saving your money for later use, with the hopes of a much bigger payoff down the road. These different parts of the brain get linked together and something like a feedback loop is established. But for all the mental chaos preceding that decision, the way a single neuron fires is a reliable predictor of what the choice ultimately is.

In experiments with monkeys and rewards, researchers found that a particular brain cell always acted one way if the monkey had chosen to take the immediate gratification - as monkeys tend to do - and always acted another way if the monkey opted for a larger, delayed reward. Decision-making involves different parts of the basal ganglia and the prefrontal cortex, but this single neuron is the one constant actor in all decision-making.

Yale neurobiologist Daeyeol Lee explains what's going on here:

"In the instant before the choice is made, we can predict the outcome of the decision by listening to the firing activity in a single neuron. We don't know the anatomical basis of lots of the psychiatric disorders, problem gambling or impulsive behavior. Now we are starting to pinpoint those areas, even down to individual neurons."

It's still early days yet, so we don't have a full grasp of how this research on monkeys will carry over to humans, or what pinpointing decision-making on a neuronal level could mean for helping people who struggle with this type of decision-making. Either way, this is a big breakthrough for linking up complex mental processes with discrete physical activity.